This disclosure relates to an insert for a die casting apparatus, and in particular, to an insert that retards erosion of a shot sleeve bore used in the die casting apparatus.
Die-casting is a common used technology for manufacturing material articles. Typically, the die casting apparatus includes a pair of die halves each formed with a void corresponding to a portion of the article to be cast. When the two die halves are brought together in proper alignment, their respective voids cooperate to form a die cavity corresponding to the shape of the article to be cast. Molten material is introduced into the die cavity and allowed to cure—typically by cooling the molten material to allow it to solidify. Once the material is sufficiently cured, the die halves are opened and the cast article is removed.
The die cast apparatus includes a shot sleeve to inject the molten material into the die cavity. This shot sleeve defines an internal sleeve bore communicating with the die cavity. The shot sleeve further includes a pour hole that accepts the molten material and directs the molten material to the sleeve bore. A plunger reciprocates within the sleeve bore to inject or force the molten material into the die cavity, wherein a hydraulic cylinder reciprocates the plunger via a plunger rod. Extension of the plunger injects the molten material within the shot sleeve into the die cavity. Retraction of the plunger withdraws the plunger to permit filling the shot sleeve for the next shot of molten material.
When the molten material flows through the pour hole and into the sleeve bore, the molten material erodes the material of the sleeve bore opposite the pour hole due to the temperature of molten material and due to the material composition of the sleeve bore. This heat erosion is a major cause of shot sleeve failure. Current methods to minimize erosion include using heavy walls for the shot sleeve, nitiriding the shot sleeve, lowering material temperatures and using water-cooling. These methods do not provide sufficient erosion protection. Additionally, these methods require costly equipment to minimize erosion. Furthermore, these methods require substantial production and maintenance costs for the shot sleeve.
Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.